I am so sad right now

Well, for the past year we have been involved in my cousins childs life. She was a 7 month old and in foster care. My husband and I really wanted to adopt and were anxious to get her. We spent months driving for visits( 2 hours away and then back 1-3 times a week), missing work, setting up her room and finally got her just before Christmas. We were noticing while having her on weekends and visits that she doesnt give eye contact, doesnt like to be held of touched, is angry and screams all the time. The foster mother (who had 4 other children and sat for an additonal 5 every day) said oh, she is not like that with us. She snuggles and falls asleep in our arms every night. OK- so maybe its us? We head forward and still have the same issues. She wont look us in the eye, wont say mommy, loves my DH more than me, goes right to him. I found RAD symptoms online and thought she might have this. I talked to her social worker and gaurdian ad litem. OH NO- we do not want to LABEL children with that. Its a bunch of nonsense and she just needs time with you. OK, I get her into the BEST caregiver I can. I really love this woman. She has adopted 4 children and been taking in foster children for 20 years. She is strong and loving and her children are clean, respectful, loving, and really care for the little ones too. So, I placed her here and said I really think she might have RAD and told my caregiver about it. She had one with this also. So, I have her here for months and although she is a really rough baby, my DH and I fool ourselves. She is getting better, right? Oh sure. See, she smiles now and plays peek-a-boo (never mind that if you stop when she doesnt want to she throws herself of the floor and screams bloody murder). So, this is how life goes on. We go on a vacation and come back and a few weeks later, my caregiver says. I have to talk to you. I dont think I can continue to watch you little one. I am finding her constant screaming, defiant behavior is taking an emotional toll on me. At the end of the day my noise quotient is met and I am short with my other children. I believe that you are right this child has RAD and well, I have to tell you, I would consider long and hard if I would continue with this adoption. She said this in a loving way (like she always is). SHe really cares about us and has seen it all. She said she was so upset, she has never had to let a child go. Every child she has had in her home she would scoop up in a min if they were avail.- until now, until ours. I felt like I was hit in the face with a baseball bat. I still feel that way. I went home and had a long long talk with DH. He has been feeling this way for awhile and doesnt think he can do it. He loves her but it is just so draining and we get so little back. I am examining and examining the past 8 months and thinking really, little has changed in her behaviors. They are a little different cuz she is older but they make us feel the same. So, after MUCH crying, soul serching, talking to relatives, more talks with DH and her caregiver, reading these boards and what you all go through on a daily basis. My DH and I have decided we have to give our little one up. We have a daughter naturally (6) and we really think we have to do what is in her best interest. I think if I had no other child, I wouldnt make this decision but I have to for my other one. I dont want her ignored (like we have been doing for the last year). I manage my little ones behavior by giving in to whatever she demands and make my other daughter do the same. Even if it is not fair. So, the decision is made, we contact the social worker, she may have a place for her in as little as a few day and as much as a few weeks. I am literally a wreck, crying all the time, cant sleep, regretting this already, clinging to her, wanting an instant change in her, praying, bargaining, you name it. WHAT THE HELL DO I DO NOW? I LOVE this little girl. I feel like the most awful person in the world. I hate myself. I did this because I wanted this baby sooo bad. And I have her. All I need is to sign. And I cant, knowing that I cant live through this forever. Knowing the therapies and that I CANT give up everything. I own a small business and cant go to appt. after appt. without losing my business. I cant co-sleep and still have that bonding relationship with DH. I have tries, showers together for the past months, feeding her out of my hands only, holding her as much as she will let me, holding her and facing me so we get eyecontact for an hour (even though she screams the whole time). Am I doing the right thing? I need help.